1. Field of the Invention
The present invention relates to a liquid container, more specifically to a liquid container wherein information relating to a state of the liquid container, such as a remaining amount of ink in an ink tank used on an ink jet printing apparatus is detected by a light-emitting means, for example, LED.
2. Description of the Related Art
Recently, as digital cameras have widely prevailed, uses are increasing wherein the printing is carried out while directly connecting a digital camera to a printer as a recording device without the intervention of a a personal computer (PC). Such a printing is called as a “camera direct printing”. Further, a printing method is also increasing wherein a card type information storing medium used for the digital camera in a detachable manner is directly mounted to a printer so that data are transferred and printed. This is called as a “card direct printing” Also, a so-called multifunction printer has quickly been prevailing in the market, wherein a printer is integrated with a scanner to have a copying function without the intervention of PC, as well as the above-mentioned direct printing function.
In an ink jet printer, there are cases wherein a user desires to know information relating to individual ink tank such as a mounting state of the ink tank or a remaining amount of ink in the ink tank or it is desirable to inform such information to the user. For example, if the user knows that the remaining amount of ink in the ink tank is little, it is possible to avoid an accident wherein the printing is substantially impossible during the printing operation due to the lack of ink, by replacing the old ink tank with a fresh one prior to beginning the printing operation.
Conventionally, such information is informed to the user by transferring the same to a PC connected to the printer and being displayed on a monitor of the PC. Contrarily, when the printing is carried out without the intervention of the PC, it is thought that a display is provided in a printer body to display such information. The provision of the display, however, is not always desirable since it causes to increase a production cost and enlarge a size of the printer, as well as requires to change a design of the printer. Also, if the display is provided, it is not certain that the user clearly seizes the state of the ink tank at a glance.
In the prior art, a display element such as an LED has been known as means for informing a state of the ink tank to the user. In Japanese Patent Application Laid-open No. 4-275156 (1992), it is described that two LEDs are provided in an ink tank formed integral with a printing head, and are turned on, respectively, in correspondence to two stages of the remaining amount of ink. More concretely, an ink cartridge in which the ink tank is integral with the printing head is provided with means for counting the number of electric switchings of the printing head and means for storing the counted number. Further, the ink cartridge is provided with an LED for displaying a near end, capable of lighting when the accumulated value of the counted number reaches a near end-determining value, and an ink end LED capable of lighting when an ink end-determining value has been reached, so that the state of the ink tank is informed to the user.
Similarly, in Japanese Patent Application Laid-open No. 2002-301829, a lamp is described, provided in an ink tank or a carriage for mounting the same, capable of lighting in correspondence to the remaining amount of ink. Also, in this patent document, the above-mentioned lamp is provided in each of four ink tanks used in a printing apparatus.
On the other hand, in accordance with the recent requirement for the further improvement in image quality, light magenta or light cyan ink has been used in addition to the conventional four colors; i.e., black, yellow, magenta and cyan. Further, the use of a so-called particular color ink such as red or blue ink has been proposed. In such a case, the ink jet printer must be provided with 7 to 8 ink tanks. Thereupon, a mechanism is necessary for preventing the respective ink tank from being mounted to an erroneous position. In Japanese Patent Application Laid-open No. 2001-253087, a structure is disclosed wherein the mutual engagement shapes between mounting portions of a carriage and the respective ink tanks are different from each other. Thereby, it is possible to prevent the ink tank from being mounted to an erroneous position.
In the above-mentioned Japanese Patent Application Laid-open No. 4-275156 (1992), a structure of an ink cartridge is disclosed, wherein an LED is attached to a printed circuit board (PCB) for carrying out the electric communication with a printer body. According to such a structure, however, it is necessary to dispose the PCB to a position at which the LED is easily visible by the user. In addition thereto, it is necessary to provide an electric connecting part in the PCB for the electric communication with the printer body. Therefor, there is a problem in that the degree of arrangement freedom of each of the LED and the electric connecting part is restricted. While it is thought to provide a large-sized PCB for covering both preferable positions for the electric connecting part and the LED, the production cost rises therefor. When the structure disclosed in Japanese Patent Application Laid-open No. 4-275156 (1992) is applied to the printer capable of mounting a plurality of independent ink tanks for the respective colors, a structure for mounting the ink tanks onto the printer is limited. Accordingly, it is necessary either to minimize a substantial volume of the respective ink tank or to enlarge a size of the printer.
On the other hand, while there is the disclosure in Japanese Patent Application Laid-open No. 2002-301829 in that an ink alarming lamp for the ink tank is provided at a place easily visible by the user, a preferable structure for supplying a power or signals to the ink alarming lamp is not described. FIGS. 6 to 8 thereof suggest that the ink jet printing apparatus and the ink alarming lamp are connected to each other by conductor wires. However, the conductor wires in correspondence to the number of the ink alarming lamps are necessary, which complicates the wiring arrangement not only to cause the production cost to rise but also to deteriorate the visibility of the lamps by the conductor wires or the connection thereof. Also, in FIGS. 6 and 7 of Japanese Patent Application Laid-open No. 2002-301829, a structure is disclosed in which the ink alarming lamp is provided on an attaching lever which is a movable member operative for attaching the ink tank on the carriage. In this case, however, the arrangement of the conductor wires is further complicated to cause the production cost to rise and also the attachment/detachment of the ink tank becomes difficult.
These problems have been further significant because the position at which the display is carried out to be visible by the user is preferably limited to the location or in the vicinity of operative means for the attachment/detachment of the ink tanks, due to the minimization in size or the multifunctioning of the printer. Particularly, in a multifunction printer carrying a scanner in the upper portion of the printer, the display position is more restricted whereby the visibility and the operability are further demanded.
The display is not only visible by the user but also used for the control carried out by the printer body. In this regard, the present inventors have known the following problems.
As described above, a structure wherein lamps are provided in ink tanks is described in Japanese Patent Application Laid-open No. 2002-301829. Even in this case, however, when the control section of the printer body recognizes an ink tank in which an amount of ink remaining therein is insufficient, it is necessary to specify such an ink tank to be supplied with a signal for the purpose of lighting the lamp based on such the recognition. For example, when the ink tank has been mounted at an erroneous position, there might be a possibility in that another ink tank in which a sufficient amount of ink remains is displayed as no ink remains therein. Accordingly, when light-emitting control of the display such as a lamp is carried out, it is necessary as a prerequisite to identify the position of the ink tank to be mounted.
As a structure for identifying the position of the ink tank, Japanese Patent Application Laid-open No. 2001-253087 describes that shapes of the mounting section and the ink tank to be engaged with each other are differentiated in every mounting positions. In this case, however, it is necessary to manufacture differently shaped ink tanks in correspondence to the respective ink colors or kinds, which is disadvantageous in production cost and/or efficiency on the recent trend that the number of ink tanks or kind of ink colors increases.
To solve such problems, the light-emitting control of individual LED is carried out in each of a plurality of ink tanks, based on an output state of a light receiver section fixed in the printer, to identify the position at which the ink tank is mounted. In such a structure, the LED in the ink tank has two functions for emitting a light beam to the user for informing the state of the ink tank and for emitting a light beam to the light receiver section to identify the position of the ink tank.
In this case, if an amount of emitted light is small, it may be difficult to be visible by the user although being sufficient for the light receiver section. Contrarily, if the amount of emitted light is excessively large, an error is liable to occur between the adjacent ink tanks, resulting in the difficulty in the correct identification of the ink tank. This is also true to the light receiver section in that it may receive the light not emitted from the correct ink tank but from that adjacent thereto.
Accordingly, it is preferable to employ a structure wherein the light emitted from the display section correctly reaches both the user and the light receiver section.